CA1108432A - Automatic gas flow control apparatus for an atomic absorption spectrometer burner - Google Patents
Automatic gas flow control apparatus for an atomic absorption spectrometer burnerInfo
- Publication number
- CA1108432A CA1108432A CA306,363A CA306363A CA1108432A CA 1108432 A CA1108432 A CA 1108432A CA 306363 A CA306363 A CA 306363A CA 1108432 A CA1108432 A CA 1108432A
- Authority
- CA
- Canada
- Prior art keywords
- oxidant
- flow
- burner
- pressure
- sample
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000010521 absorption reaction Methods 0.000 title claims description 12
- 239000007800 oxidant agent Substances 0.000 claims abstract description 125
- 230000001590 oxidative effect Effects 0.000 claims abstract description 121
- 239000000446 fuel Substances 0.000 claims abstract description 31
- 238000012544 monitoring process Methods 0.000 claims abstract description 11
- 239000000523 sample Substances 0.000 claims description 21
- 230000004044 response Effects 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 12
- 230000035945 sensitivity Effects 0.000 claims description 10
- 208000036366 Sensation of pressure Diseases 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims 1
- 239000006199 nebulizer Substances 0.000 abstract description 33
- 238000001479 atomic absorption spectroscopy Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 20
- 230000009102 absorption Effects 0.000 description 8
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 7
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 4
- 239000012488 sample solution Substances 0.000 description 4
- 230000000875 corresponding effect Effects 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- SRVJKTDHMYAMHA-WUXMJOGZSA-N thioacetazone Chemical compound CC(=O)NC1=CC=C(\C=N\NC(N)=S)C=C1 SRVJKTDHMYAMHA-WUXMJOGZSA-N 0.000 description 3
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000000306 component Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000004847 absorption spectroscopy Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 108010052322 limitin Proteins 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000001272 nitrous oxide Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2241/00—Applications
- F23N2241/16—Spectrometer burners
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
There is described a programmable gas flow control apparatus for use in atomic absorption spectroscopy. Essentially, an all pneumatic system is described which provides for a pre-determined flow of fuel and oxidant to the burner. The invention compensates for the variation in oxidant flow due to nebulizer adjustments by adjusting the oxidant flow to the auxiliary inlet of the burner. The invention utilizes a pneumatic computing relay which senses the oxidant flow to the nebulizer and simul-taneously adjusts the flow to the auxiliary inlet so that the total flow of oxidant satisfies the predetermined optimum rate.
The constant monitoring of the nebulizer line by the computing relay allows for continual adjustment of the oxidant flow to off-set subsequent adjustments.
There is described a programmable gas flow control apparatus for use in atomic absorption spectroscopy. Essentially, an all pneumatic system is described which provides for a pre-determined flow of fuel and oxidant to the burner. The invention compensates for the variation in oxidant flow due to nebulizer adjustments by adjusting the oxidant flow to the auxiliary inlet of the burner. The invention utilizes a pneumatic computing relay which senses the oxidant flow to the nebulizer and simul-taneously adjusts the flow to the auxiliary inlet so that the total flow of oxidant satisfies the predetermined optimum rate.
The constant monitoring of the nebulizer line by the computing relay allows for continual adjustment of the oxidant flow to off-set subsequent adjustments.
Description
FIELD OE TH _ NvENrrIoN
This in~ention per~ains generally to atomic absorption spectrometers, and more particularly, to an automatic gas control system for burners used in atomic .
~ absorption spectroscopy.
; - BACKGROUND OF THE INVENTION
In atomic absorption spectroscopy (see, for example, U.S~P.N. 2,847,899), the measurement of the absorption of a radiation beam at a characteristic resonant spectral line for a ~ ~ .
particular element yields a measure of the concentration of ;~ that element in an original sample solution. Presently, the '.'t" most common technique for atomizing an element for the purposes of the absorption measurement, is by introducing a li~uid sample solution of the element of interest into a gas burner wherein droplets of the solution are vaporized and the elements ultimately atomized, so as to form in the path of the apparatus ~!
radiation beam, a substantial quantity of the element of interst ~- in its atomic state.
In order to effect appropriate burning of the element- -.-:
~- 20 containing solution, the liquid mus~ be converted into a fine spray and then mixed with a fuel and oxidant gas before introduction into the burnerO The fine spray is achieved through use of a nebulizer, such as described in U.S. Patent No. 4,125,225, also assigned to the assignee herein.
A nebulizer, generally, employs a venturi-type restriction which passes rapidly-moving gas (hereinafter referred to as an oxidant~ past an opening, drawing a portion of the li~uid sample solution into the gas stream, effecting an atomizing of the liquid in the process~ The liquid is said to be aspirated by the venturi effect caused by the rapidly moving current of gas.
The ~ample laden gas or oxidant, then passes into the burner chamber where it is mixed with additional oxidant from an auxiliary inlet/ and fuel such as acetyleneO It i5 then intro-duced into the burner head where lt is ignited.
;-"" "
. ~\
The sensitivity of the absorption mea~urement is de-pendent on many factoxs~ one of which being the flame condition of the burner. IPe., the leannes~ or richness of the fuel-oxidant mixture. Also, the sensitivity of the measuremenk requires the optimization of the setting of the nebulizer which varies the amount of liquid sample aspirated by the rapidly flowing gas.
Because of the nature of the mechanism for aspirating more or less o the sample~ namely varying the flow of oxidant through the venturi-type restriction, there is lhe obvious side eEfect on the 1ame condition which has a direct e~fect on the sensiti-vity of the measurement. In prior systems, the opera~or would have to go back to the auxlliary inlet to th~ burner and vary the oxidant flow through it to compensate for the last adjustment to the nebulizer and the effect thereof on the oxidant flow into the burner.
The object of an automatic gas control system, would be to eliminate these readjustmen~ due to the adjustments of the nebulizer.
Further, an automatic gas control system should allow for the programmability of optimum analys~s parameters. E.g., with respect to the field herein discussed, namely atomic absorp-tion spectometry, the optimum ~uel-oxidant flow rates, element wave lengths, uel-oxidant characteristics, and the like, - para meters which could be optimized by ~he methods analyst in the lab -- should be maintained constant for each measurement even on differing instruments~ Desirably, the optimum values for these ~actors can be stored in a memory device, such as on magnetic cards, which can be used to program different instruments to insure optimum results.
It is therefore a primaxy object o~ this invention to provide an apparatus which will respond identically to pre-pro grammed optimum fuel-oxidant gas flow rates, irregardless of the instrument system in which employed.
3~
It is another object of thls invention to pr~vide operator-free adjustment of the oxidant flow to the auxiliary inlet of a hurner to offs~t the e~fects of nebuli~er adjust-ments on th~ oxidant flo~ therethrough.
There is yet another object of the invention to provide a pneumatic control means for adjusting the oxidant flow to the auxiliary inlet in response to nebulizer adjustments.
It is still another object of this invention to provide a pneumatic correction means which both senses a change in the flow of oxidant to the nebulizer intake and corrects the flow of the oxidant to the auxiliary inlet in response to the sensed change to said nebulizer.
SUr~MARY OF THE_INVENTION
In accordance with a broad aspect of the invention, there is provided a gas flow control system for an atomic absorption spectrometer comprising a hurner for burning a mix-ture of fuel, oxidant and sample, a mix:;ng chamber for mixing the fuel, oxidant and sample r means for supplying fuel to the mixing chamber, means for supplying a mixture of sample and oxi-dant to the mixing chamber, and auxiliary means for supplyingoxidant to the mixing chamber. Means are also provided for varying the supply of sample and oxidant mixture to the mixing chamber, and means are provided for adjusting the flow of oxi-dant through the auxiliary supply means in response to a variation in the supply of oxidant supplied by the sample and oxidant supply means such that the total oxidant flow supplied to the burner remains substantially constant.
More specifically in accordance with the invention, there is described herein, an automatic gas control apparatus for use in an atomic absorption spectrometer instrument system including a burner for burning a mixture of fuel, o~idant and an unknown element-containing sample, which comprises a fuel supply means which provides a predetermined flow of fuel to _3_ the burner based on a stored electrical signal corresponding to a previously determined optimum flow rate; a nebulizer, which introdwces a variable amount of sample, the nebulizer being adjustable to vary the sample flow so as to optimize the measured signal of the spectrometer; variable (auxiliary) oxidant supply means, the flow through which can be varied so as to make up the difference between the predetermined total flow of oxidant re~uired for a pres~ribed sensitivi-ty of the spectrometer and the varying amount supplied by the sarnple introducing means because of the adjustment feature required to optimize -the measured signal; means for measuring the flow of oxidant through both the sample introducing nebulizer and the variable oxidant supply means; and means for comparing -3a-the sensed oxidant flows to the previously determined oxidant flow requixed for a prescribed sensitivity ~ wi~h means for adjus-ting the flow of oxidant to ~he variable oxidant supply means in response to the comparison so ~.s to insure that the total flow of oxidant to the burner is maintained at the predetermined amountO
Pxeferably, the apparatus i5 suhstantially, pneumatiGally control-led. Particularly, the means for sensing the two oxidant flow rates and comparing these to the predetermined total flow rate, is done by a pneumatically operated, computing relay which further includes means for respondin~ to ~he comparison and ad-justing the oxidant flow from its inlet to outlet portr the latter in turn supplyin~ the ~ariable oxidan~ means. The result is that the total amount of oxidan~ to the burner is maintained at the predetermined amount.
BR~EF DESCRIPTION OF THE DR~WINGS
Figure 1 is an elevation view of a nebulizer-burner assembly, typically employed in atomic absorption spectrometer instrumentation.
; Figure 2 is a block diagram of the gas conkrol system in accordance with the invention~
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to Figure 1, there is shown a typical nebulizer-burner assembly used in atomic absorption spectroscopy.
It includes a cham~er 10 for mixing fuel, oxidant and the unknown element-containing sample. The chamber eeds the burner 12 which ignites the fuel, oxidant and sample mixture. Feeding the chamber is a fuel line 14 which supplies a suitable gas, e~g~ acetylene, from a regulated source.
..~ 3~
A~iallv connected to the chamber 10 i~ a nebulizer 16.
The internal configuration of the nebulizer is not shown, but is understood to be operational in a manner similar to manv such devices on the market. A typical configuration can be seen in U.S. Patent No. 4,125,225, mentioned a~ove. The nebulizer introduc~s a variable flow of the unknown element-containin~ sample into the mixing chamber~
The sample solution is contained in a beaker such as 18. Typically, the sample is an unknown metallic element in solution. The aspirating action of the venturi-type restriction in the nebulizer draws solution out of the beaker through capillary tubin~ 20. For the purpose of the discussion herein, the term "tube" or "tuhing" is understood to be des-criptive and includes any appropriate conduit found in the art.
The aspiration of the sample is achieved by rapidly-moving gas, typically travelling through the venturi restriction, - which draws the solution into the nebulizer and atomizes it into a fine spray. The rapidly-moving gas enters the nebulizer via tubing 22. Generally, this gas is referred to as the oxidant~ In a typical situation, it might be ni-trous oxide or, air.
To adjust the nebulizer for most efficient sample aspiration, the operator of the equipment, for the unit shown, would turn knob 24. This would alter the flow of sample into the assembly, but because of the nebuli~er design, there will be a corresponding effect on the flow of the oxidant entering the nebulizer through tubin~ 22. The adjustment of the nebulizer by the operator for an optimum measured signal in the spectrophotometer will vary from unit to unit, so that differing effects Oll the oxidant flow rate through tubing 22 will result.
Since the amount of oxidant supplied ~o the burner is altered, the flame condition and thus the signal measurement would be altered except for the present invention.
." ' .
3;~
. .
The nebulizer, typically, is a~ially joined to the mixin~ chamber by a sealing interface at 26.
Connected to the mixing chamber is a variable (aux-iliary) supply of oxidant. This is provided through tubing 28.
As will ~e seen hereafter in the discussion of Figure 2, the amount of oxidant supplied at this point will be equal to the difference between the total flow of oxidant predetermined, for example, by a methods analYst as necesary to insure a prescribed sensitivity, and the varying amount supplied to the chamber by the nebulizer. As clearly shown in Figure 1, in this embodiment the oxyyen is supplied through discrete first and second conduits 22 and 28 respectively.
In order to sense the flow of oxidant supplied to the nebulizer, in-line means, such as a restrictor is inserted in the oxidant supply tubing 22. The restrictor is shown at 30.
The flow rate is sensed by monitoring the pressure on either side o~ the restrictor. This is accomplished by pressure monitoring parts 32 and 34, connected into the tubing 22 and 82 ; respectively. For the indicated 1OW direction for the oxidant, the pressure at termlnal 34 would be higher than the pressure at 32.
Ports 32 and 34 are shown as being directed to a so-called 'icomputing relay" whose operation as it concerns the gas flow control system of the invention will be discussed with re-spect to Figure 2. Generally, its function is to compare the pressure differential across the restrictor 30 to a predetermined command pressure based on a prescribed sensitivitv of the spectro-meter and to adjust the oxidant flow between the auxiliary inlet [hereinabove referred to as inlet 28) and the nebulizer inlet [hereinabove referred to as inlet 22) to compensate for the var-iations of oxidant flow in 22 due to nebulizer adjustments at knob 24.
.: ,i Referrin~ now to Figure 2, there is shown in block diagram form, an arrangement of the various pneumatic components which effect the purposes of the invention. The few situations where reference numerals are identical to those employed in/
~ 10 . ' :. /
' . / .
'' /
/
., /
. /
: /
- 6a -3~
.~
Fi~ure 1, those are done to identify the same identical compon ents or tubing even though in this la~ter figure ~hey are a block dia~ram equivalent.
Considsring the fuel supply section initially, the burner fuel, ac~tylene, is supplied to the system ~ia tubing 36.
Acetylene is employed becaus~ it i5 readily available and inex-pensive, Tubing 36 is connected to a pres~ure switch 38 which se~ses a safe level before closing. Typically, the acetylene at the input might bP on the order o lS psi~, and the threshhold pressure of the switch 38 set at 7 p~igO ~ha switch directs the fuel to a pair vf solenoids via tubing 40 and 42~ The irst such ~olenoid 44 is energixed at start up and direct~ the fuel through tubing 46 to the igniter section of the burner. Once ignited, solenoid 44 is opened and the fuel is blocked from that pa~sageway.
During subsequent hurner operation, solenoid 48 is closed and the fuel directed therethrough to tubing 50 and pres-sure regulator 52~ The output of ~he regulator 54 ~ typically, would have a fuel gas pressura at 12 psig~ This pressure level is the maximum that can be employed in the burner because of the ins~ability of acetylene above that pressure.
The regulator is connected to a volume booster 56. A
typical unit would be a model 20, manufactured by the Industrial Products Division of the Fairchild Company. It responds to a command pressure on line 58, in order to further reduce the pres-sur~ of the acetylene from 12 psig down to a value determined previously to be optimum for spectrometer sensitivity. For example, the pressure of the gas in tubing 57, typically, will be a~ 6 psigO The tubing 57 i~ connected to the fuel inlet duct 14 - previou~ly referred o in Figure 1.
The command pressure input to the volume booster 56 is supplied by a voltage to pressure transducer 60~ The latter rec~ives an analog signal on input line 62 from a digital ko analo~ converter 6~. The D/A converter is supplied, via line 66, with a digital word permanently stored on a typical memory device such as a magnetic card or disc~ The digital word xepresents the optLmum flow of the fuel as pr~viously d~termined by a methods analyst in arriving at opt~mum parameters ~or the ~ystem, The volume booster, in a situation where acetylene is ~mployed, for example, is a non-relieving type, i.e., it would bleed off the necessary amount of acetylene into the burner to achieve the commanded pressure diferential and not into the air as migh~ be ~he case with relievi~y~type boosters.
The analog signal appearing on line 62 to the trans-ducer 6Q, typically, is on the order of 0 to 9 v~olts, with the corresponding pressure out of t~e ~ran~ducer in tubing 58, be-tween 3 and 15 psig, ~ ty~ica1 transducer is model T5109, again manufactured by the Industrial Produc~s Div.ision of the Fairchild Company.
Thus, there has been described means for supplyinq a predetermined flow rate of fuel for the burner in response to a pre-existing command. Thus optLmi~ation of a critical parameter is assured.
:~ The total oxidant supply to the system appears in tubing 68 and wses as its source ei~her a supply of nitrous oxide entering on line ~9, ~hrough pres~ure switch 70 and solenoid 72, or air on line 73 through pressure switch 74 an~ solenoid 76. The pressure ~ switches 70 and 74, typically, have a setting at 25 psig~ De~
: pending on the oxidant to be u~ed, either solenoid 72 or 76 would be selected by appropriate control.
The oxidant in tu~ing 68 is supplied to a pressuxe re-gulator 78 which maintains a prassure level in tubing 80 at, typi cally, 32 psig. Tubing Y0 i5 connected by a T-connectionat tubing 82 and 84. Tubin~ 82 ~pre~iou~ly referred to with respect ~o Figllre 1) is connected to restrictor 300 As discussed earlier~, g the down stream side of the restrictor is supplied to the oxidant inlet on the nebulizer via tubing 22.
86 refers to a pneumatic computing means, known typic-ally as a computing rela~,7. A standard unit is a model 22 computing relay as manufactured by the Industrial Products Division of Fairchild Company. It likewise generally, would be a non-relieving type. The computing relay includes an oxidant inlet port~ S, and outlet port, P~ These are connected, respectivel.y~to tubing 84, the variable oxidant flow supply, and the auxiliary inlet 28, to the mixing chamber~
~ Further, the relay includesports C and A which are ~ connected respectively to the pressure monitoring ports on either side of the in-line restrictor 30.
Also, the computing relav includes a comrnand pressure port B which is connected to a command pressure supply in line 88 which emanates from a voltage to pressure transducer 90.
The latter provides a command pressure on its output from, typically, 3 to 15 psig in response to an analoy signal of 0 to 9 volts, as received on input line 92. The analog signal is produced by a digital to analog converter 94 and is pro-portional to a predetermined digital word received on input electrical line 96. The digital word appearing on line 96 would be stored, much like the signal representing the pre-determined fuel rate on a memory device such as a magnetic card or disc. Its value, again, would be previousl~7 determined by a methods analyst in arriving at optimum values for the various parameters necessary to be considerd in optimizing the sensitivity of the instrument.
The input pressure supply for the voltage transducer-90, and the previously described transducer 60, is developedfrom an air supply line and is inputted to the transducer 90 on line 98. Line 98 is connected to a pressure regulator 100 which is connected by line 102 to the previously discussed pressure switch 74 on the air input line. The r~gulator 100 maintains the pressure in lines 98 and 104 ~ the supply lines for the transducers, at an adequate pressure necessary for the command function performed by each.
Typically, the pressure in those lines might be on the order o
This in~ention per~ains generally to atomic absorption spectrometers, and more particularly, to an automatic gas control system for burners used in atomic .
~ absorption spectroscopy.
; - BACKGROUND OF THE INVENTION
In atomic absorption spectroscopy (see, for example, U.S~P.N. 2,847,899), the measurement of the absorption of a radiation beam at a characteristic resonant spectral line for a ~ ~ .
particular element yields a measure of the concentration of ;~ that element in an original sample solution. Presently, the '.'t" most common technique for atomizing an element for the purposes of the absorption measurement, is by introducing a li~uid sample solution of the element of interest into a gas burner wherein droplets of the solution are vaporized and the elements ultimately atomized, so as to form in the path of the apparatus ~!
radiation beam, a substantial quantity of the element of interst ~- in its atomic state.
In order to effect appropriate burning of the element- -.-:
~- 20 containing solution, the liquid mus~ be converted into a fine spray and then mixed with a fuel and oxidant gas before introduction into the burnerO The fine spray is achieved through use of a nebulizer, such as described in U.S. Patent No. 4,125,225, also assigned to the assignee herein.
A nebulizer, generally, employs a venturi-type restriction which passes rapidly-moving gas (hereinafter referred to as an oxidant~ past an opening, drawing a portion of the li~uid sample solution into the gas stream, effecting an atomizing of the liquid in the process~ The liquid is said to be aspirated by the venturi effect caused by the rapidly moving current of gas.
The ~ample laden gas or oxidant, then passes into the burner chamber where it is mixed with additional oxidant from an auxiliary inlet/ and fuel such as acetyleneO It i5 then intro-duced into the burner head where lt is ignited.
;-"" "
. ~\
The sensitivity of the absorption mea~urement is de-pendent on many factoxs~ one of which being the flame condition of the burner. IPe., the leannes~ or richness of the fuel-oxidant mixture. Also, the sensitivity of the measuremenk requires the optimization of the setting of the nebulizer which varies the amount of liquid sample aspirated by the rapidly flowing gas.
Because of the nature of the mechanism for aspirating more or less o the sample~ namely varying the flow of oxidant through the venturi-type restriction, there is lhe obvious side eEfect on the 1ame condition which has a direct e~fect on the sensiti-vity of the measurement. In prior systems, the opera~or would have to go back to the auxlliary inlet to th~ burner and vary the oxidant flow through it to compensate for the last adjustment to the nebulizer and the effect thereof on the oxidant flow into the burner.
The object of an automatic gas control system, would be to eliminate these readjustmen~ due to the adjustments of the nebulizer.
Further, an automatic gas control system should allow for the programmability of optimum analys~s parameters. E.g., with respect to the field herein discussed, namely atomic absorp-tion spectometry, the optimum ~uel-oxidant flow rates, element wave lengths, uel-oxidant characteristics, and the like, - para meters which could be optimized by ~he methods analyst in the lab -- should be maintained constant for each measurement even on differing instruments~ Desirably, the optimum values for these ~actors can be stored in a memory device, such as on magnetic cards, which can be used to program different instruments to insure optimum results.
It is therefore a primaxy object o~ this invention to provide an apparatus which will respond identically to pre-pro grammed optimum fuel-oxidant gas flow rates, irregardless of the instrument system in which employed.
3~
It is another object of thls invention to pr~vide operator-free adjustment of the oxidant flow to the auxiliary inlet of a hurner to offs~t the e~fects of nebuli~er adjust-ments on th~ oxidant flo~ therethrough.
There is yet another object of the invention to provide a pneumatic control means for adjusting the oxidant flow to the auxiliary inlet in response to nebulizer adjustments.
It is still another object of this invention to provide a pneumatic correction means which both senses a change in the flow of oxidant to the nebulizer intake and corrects the flow of the oxidant to the auxiliary inlet in response to the sensed change to said nebulizer.
SUr~MARY OF THE_INVENTION
In accordance with a broad aspect of the invention, there is provided a gas flow control system for an atomic absorption spectrometer comprising a hurner for burning a mix-ture of fuel, oxidant and sample, a mix:;ng chamber for mixing the fuel, oxidant and sample r means for supplying fuel to the mixing chamber, means for supplying a mixture of sample and oxi-dant to the mixing chamber, and auxiliary means for supplyingoxidant to the mixing chamber. Means are also provided for varying the supply of sample and oxidant mixture to the mixing chamber, and means are provided for adjusting the flow of oxi-dant through the auxiliary supply means in response to a variation in the supply of oxidant supplied by the sample and oxidant supply means such that the total oxidant flow supplied to the burner remains substantially constant.
More specifically in accordance with the invention, there is described herein, an automatic gas control apparatus for use in an atomic absorption spectrometer instrument system including a burner for burning a mixture of fuel, o~idant and an unknown element-containing sample, which comprises a fuel supply means which provides a predetermined flow of fuel to _3_ the burner based on a stored electrical signal corresponding to a previously determined optimum flow rate; a nebulizer, which introdwces a variable amount of sample, the nebulizer being adjustable to vary the sample flow so as to optimize the measured signal of the spectrometer; variable (auxiliary) oxidant supply means, the flow through which can be varied so as to make up the difference between the predetermined total flow of oxidant re~uired for a pres~ribed sensitivi-ty of the spectrometer and the varying amount supplied by the sarnple introducing means because of the adjustment feature required to optimize -the measured signal; means for measuring the flow of oxidant through both the sample introducing nebulizer and the variable oxidant supply means; and means for comparing -3a-the sensed oxidant flows to the previously determined oxidant flow requixed for a prescribed sensitivity ~ wi~h means for adjus-ting the flow of oxidant to ~he variable oxidant supply means in response to the comparison so ~.s to insure that the total flow of oxidant to the burner is maintained at the predetermined amountO
Pxeferably, the apparatus i5 suhstantially, pneumatiGally control-led. Particularly, the means for sensing the two oxidant flow rates and comparing these to the predetermined total flow rate, is done by a pneumatically operated, computing relay which further includes means for respondin~ to ~he comparison and ad-justing the oxidant flow from its inlet to outlet portr the latter in turn supplyin~ the ~ariable oxidan~ means. The result is that the total amount of oxidan~ to the burner is maintained at the predetermined amount.
BR~EF DESCRIPTION OF THE DR~WINGS
Figure 1 is an elevation view of a nebulizer-burner assembly, typically employed in atomic absorption spectrometer instrumentation.
; Figure 2 is a block diagram of the gas conkrol system in accordance with the invention~
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to Figure 1, there is shown a typical nebulizer-burner assembly used in atomic absorption spectroscopy.
It includes a cham~er 10 for mixing fuel, oxidant and the unknown element-containing sample. The chamber eeds the burner 12 which ignites the fuel, oxidant and sample mixture. Feeding the chamber is a fuel line 14 which supplies a suitable gas, e~g~ acetylene, from a regulated source.
..~ 3~
A~iallv connected to the chamber 10 i~ a nebulizer 16.
The internal configuration of the nebulizer is not shown, but is understood to be operational in a manner similar to manv such devices on the market. A typical configuration can be seen in U.S. Patent No. 4,125,225, mentioned a~ove. The nebulizer introduc~s a variable flow of the unknown element-containin~ sample into the mixing chamber~
The sample solution is contained in a beaker such as 18. Typically, the sample is an unknown metallic element in solution. The aspirating action of the venturi-type restriction in the nebulizer draws solution out of the beaker through capillary tubin~ 20. For the purpose of the discussion herein, the term "tube" or "tuhing" is understood to be des-criptive and includes any appropriate conduit found in the art.
The aspiration of the sample is achieved by rapidly-moving gas, typically travelling through the venturi restriction, - which draws the solution into the nebulizer and atomizes it into a fine spray. The rapidly-moving gas enters the nebulizer via tubing 22. Generally, this gas is referred to as the oxidant~ In a typical situation, it might be ni-trous oxide or, air.
To adjust the nebulizer for most efficient sample aspiration, the operator of the equipment, for the unit shown, would turn knob 24. This would alter the flow of sample into the assembly, but because of the nebuli~er design, there will be a corresponding effect on the flow of the oxidant entering the nebulizer through tubin~ 22. The adjustment of the nebulizer by the operator for an optimum measured signal in the spectrophotometer will vary from unit to unit, so that differing effects Oll the oxidant flow rate through tubing 22 will result.
Since the amount of oxidant supplied ~o the burner is altered, the flame condition and thus the signal measurement would be altered except for the present invention.
." ' .
3;~
. .
The nebulizer, typically, is a~ially joined to the mixin~ chamber by a sealing interface at 26.
Connected to the mixing chamber is a variable (aux-iliary) supply of oxidant. This is provided through tubing 28.
As will ~e seen hereafter in the discussion of Figure 2, the amount of oxidant supplied at this point will be equal to the difference between the total flow of oxidant predetermined, for example, by a methods analYst as necesary to insure a prescribed sensitivity, and the varying amount supplied to the chamber by the nebulizer. As clearly shown in Figure 1, in this embodiment the oxyyen is supplied through discrete first and second conduits 22 and 28 respectively.
In order to sense the flow of oxidant supplied to the nebulizer, in-line means, such as a restrictor is inserted in the oxidant supply tubing 22. The restrictor is shown at 30.
The flow rate is sensed by monitoring the pressure on either side o~ the restrictor. This is accomplished by pressure monitoring parts 32 and 34, connected into the tubing 22 and 82 ; respectively. For the indicated 1OW direction for the oxidant, the pressure at termlnal 34 would be higher than the pressure at 32.
Ports 32 and 34 are shown as being directed to a so-called 'icomputing relay" whose operation as it concerns the gas flow control system of the invention will be discussed with re-spect to Figure 2. Generally, its function is to compare the pressure differential across the restrictor 30 to a predetermined command pressure based on a prescribed sensitivitv of the spectro-meter and to adjust the oxidant flow between the auxiliary inlet [hereinabove referred to as inlet 28) and the nebulizer inlet [hereinabove referred to as inlet 22) to compensate for the var-iations of oxidant flow in 22 due to nebulizer adjustments at knob 24.
.: ,i Referrin~ now to Figure 2, there is shown in block diagram form, an arrangement of the various pneumatic components which effect the purposes of the invention. The few situations where reference numerals are identical to those employed in/
~ 10 . ' :. /
' . / .
'' /
/
., /
. /
: /
- 6a -3~
.~
Fi~ure 1, those are done to identify the same identical compon ents or tubing even though in this la~ter figure ~hey are a block dia~ram equivalent.
Considsring the fuel supply section initially, the burner fuel, ac~tylene, is supplied to the system ~ia tubing 36.
Acetylene is employed becaus~ it i5 readily available and inex-pensive, Tubing 36 is connected to a pres~ure switch 38 which se~ses a safe level before closing. Typically, the acetylene at the input might bP on the order o lS psi~, and the threshhold pressure of the switch 38 set at 7 p~igO ~ha switch directs the fuel to a pair vf solenoids via tubing 40 and 42~ The irst such ~olenoid 44 is energixed at start up and direct~ the fuel through tubing 46 to the igniter section of the burner. Once ignited, solenoid 44 is opened and the fuel is blocked from that pa~sageway.
During subsequent hurner operation, solenoid 48 is closed and the fuel directed therethrough to tubing 50 and pres-sure regulator 52~ The output of ~he regulator 54 ~ typically, would have a fuel gas pressura at 12 psig~ This pressure level is the maximum that can be employed in the burner because of the ins~ability of acetylene above that pressure.
The regulator is connected to a volume booster 56. A
typical unit would be a model 20, manufactured by the Industrial Products Division of the Fairchild Company. It responds to a command pressure on line 58, in order to further reduce the pres-sur~ of the acetylene from 12 psig down to a value determined previously to be optimum for spectrometer sensitivity. For example, the pressure of the gas in tubing 57, typically, will be a~ 6 psigO The tubing 57 i~ connected to the fuel inlet duct 14 - previou~ly referred o in Figure 1.
The command pressure input to the volume booster 56 is supplied by a voltage to pressure transducer 60~ The latter rec~ives an analog signal on input line 62 from a digital ko analo~ converter 6~. The D/A converter is supplied, via line 66, with a digital word permanently stored on a typical memory device such as a magnetic card or disc~ The digital word xepresents the optLmum flow of the fuel as pr~viously d~termined by a methods analyst in arriving at opt~mum parameters ~or the ~ystem, The volume booster, in a situation where acetylene is ~mployed, for example, is a non-relieving type, i.e., it would bleed off the necessary amount of acetylene into the burner to achieve the commanded pressure diferential and not into the air as migh~ be ~he case with relievi~y~type boosters.
The analog signal appearing on line 62 to the trans-ducer 6Q, typically, is on the order of 0 to 9 v~olts, with the corresponding pressure out of t~e ~ran~ducer in tubing 58, be-tween 3 and 15 psig, ~ ty~ica1 transducer is model T5109, again manufactured by the Industrial Produc~s Div.ision of the Fairchild Company.
Thus, there has been described means for supplyinq a predetermined flow rate of fuel for the burner in response to a pre-existing command. Thus optLmi~ation of a critical parameter is assured.
:~ The total oxidant supply to the system appears in tubing 68 and wses as its source ei~her a supply of nitrous oxide entering on line ~9, ~hrough pres~ure switch 70 and solenoid 72, or air on line 73 through pressure switch 74 an~ solenoid 76. The pressure ~ switches 70 and 74, typically, have a setting at 25 psig~ De~
: pending on the oxidant to be u~ed, either solenoid 72 or 76 would be selected by appropriate control.
The oxidant in tu~ing 68 is supplied to a pressuxe re-gulator 78 which maintains a prassure level in tubing 80 at, typi cally, 32 psig. Tubing Y0 i5 connected by a T-connectionat tubing 82 and 84. Tubin~ 82 ~pre~iou~ly referred to with respect ~o Figllre 1) is connected to restrictor 300 As discussed earlier~, g the down stream side of the restrictor is supplied to the oxidant inlet on the nebulizer via tubing 22.
86 refers to a pneumatic computing means, known typic-ally as a computing rela~,7. A standard unit is a model 22 computing relay as manufactured by the Industrial Products Division of Fairchild Company. It likewise generally, would be a non-relieving type. The computing relay includes an oxidant inlet port~ S, and outlet port, P~ These are connected, respectivel.y~to tubing 84, the variable oxidant flow supply, and the auxiliary inlet 28, to the mixing chamber~
~ Further, the relay includesports C and A which are ~ connected respectively to the pressure monitoring ports on either side of the in-line restrictor 30.
Also, the computing relav includes a comrnand pressure port B which is connected to a command pressure supply in line 88 which emanates from a voltage to pressure transducer 90.
The latter provides a command pressure on its output from, typically, 3 to 15 psig in response to an analoy signal of 0 to 9 volts, as received on input line 92. The analog signal is produced by a digital to analog converter 94 and is pro-portional to a predetermined digital word received on input electrical line 96. The digital word appearing on line 96 would be stored, much like the signal representing the pre-determined fuel rate on a memory device such as a magnetic card or disc. Its value, again, would be previousl~7 determined by a methods analyst in arriving at optimum values for the various parameters necessary to be considerd in optimizing the sensitivity of the instrument.
The input pressure supply for the voltage transducer-90, and the previously described transducer 60, is developedfrom an air supply line and is inputted to the transducer 90 on line 98. Line 98 is connected to a pressure regulator 100 which is connected by line 102 to the previously discussed pressure switch 74 on the air input line. The r~gulator 100 maintains the pressure in lines 98 and 104 ~ the supply lines for the transducers, at an adequate pressure necessary for the command function performed by each.
Typically, the pressure in those lines might be on the order o
2 0 psig .
The computing relay is a well known device which employs chambers and diaphragms ~o solve the equation P=A~B-C~K, Where P is the pressure in the oxidant outlet port, A
and C are the pressures on either side of the line restrictor, and B is the command pressure out of transducer 90.
K i~ an ofset which is effected by a mechanical adjus-tment on the computing relay unit~ It is set initially so as to assure a~ port P~ a sufficiant pressure to provide the lowest flow ~ rate of oxidant in response to the lowest digital command on line : 96.
The compllting relay is thus seen to perorm the function of sensing and comparing the flow of oxidant to the nebulizer and and the auxiliary oxidant supply means ~o a pxedetermined com mand flow rate for the oxidant as represented by the pressure on line 88. The relay adjusts the ~low of oxidant to the auxiliary inlet in response to this comparison and does so and continues to readjust the 10w thereto as it sen~es variations in the flow to the nebulizer across the restrictor 30.
Other variation~ of the above embodiment would be ap parent to those skilled in the art in light of the above. For example, inskeacl of employing ~a computing relay~ means for sen ~ing ~he flow of oxidan~ ~o the sample introducing means (nebu-lizer), in oxidant supply line, 22, and as well as means sensing the flow in line 28 could be employed. The~e might, typically, produce elec~rical s.~gnals which would then be compared with the command electrical signalO Valves in ~ach of the supply lines - could be provided which would be operated upon by the compared electrical signals 50 as to vary the amount of oxidant f lowin~
into ~he auxiliary based on th~ compared readingsO
The advantage of the present technique, is that the computing relay can both sense the variations in oxidant f low to the nebulizer and effect an adjustment in accordance therewith to the oxidant flow to the auxiliary inlet.
The above described embc~diment is not to be construed as limitin~ the extent and breadth o th~3 invesltion which ls defined in the appended Claims,
The computing relay is a well known device which employs chambers and diaphragms ~o solve the equation P=A~B-C~K, Where P is the pressure in the oxidant outlet port, A
and C are the pressures on either side of the line restrictor, and B is the command pressure out of transducer 90.
K i~ an ofset which is effected by a mechanical adjus-tment on the computing relay unit~ It is set initially so as to assure a~ port P~ a sufficiant pressure to provide the lowest flow ~ rate of oxidant in response to the lowest digital command on line : 96.
The compllting relay is thus seen to perorm the function of sensing and comparing the flow of oxidant to the nebulizer and and the auxiliary oxidant supply means ~o a pxedetermined com mand flow rate for the oxidant as represented by the pressure on line 88. The relay adjusts the ~low of oxidant to the auxiliary inlet in response to this comparison and does so and continues to readjust the 10w thereto as it sen~es variations in the flow to the nebulizer across the restrictor 30.
Other variation~ of the above embodiment would be ap parent to those skilled in the art in light of the above. For example, inskeacl of employing ~a computing relay~ means for sen ~ing ~he flow of oxidan~ ~o the sample introducing means (nebu-lizer), in oxidant supply line, 22, and as well as means sensing the flow in line 28 could be employed. The~e might, typically, produce elec~rical s.~gnals which would then be compared with the command electrical signalO Valves in ~ach of the supply lines - could be provided which would be operated upon by the compared electrical signals 50 as to vary the amount of oxidant f lowin~
into ~he auxiliary based on th~ compared readingsO
The advantage of the present technique, is that the computing relay can both sense the variations in oxidant f low to the nebulizer and effect an adjustment in accordance therewith to the oxidant flow to the auxiliary inlet.
The above described embc~diment is not to be construed as limitin~ the extent and breadth o th~3 invesltion which ls defined in the appended Claims,
Claims (12)
1. A gas flow control system for an atomic absorption spectrometer comprising:
a burner for burning a mixture of fuel, oxidant and sample, a mixing chamber for mixing fuel, oxidant and sample, means for supplying fuel to said mixing chamber, means for supplying a mixture of sample and oxidant to said mixing chamber, auxiliary means for supplying oxidant to said mixing chamber, means for varying the supply of the sample and oxidant mixture to the mixing chamber, and means for adjusting the flow of oxidant through said auxiliary supply means in response to a variation in the supply of oxidant supplied by said sample and oxidant supply means such that the total oxidant flow supplied to said burner remains substantially constant.
a burner for burning a mixture of fuel, oxidant and sample, a mixing chamber for mixing fuel, oxidant and sample, means for supplying fuel to said mixing chamber, means for supplying a mixture of sample and oxidant to said mixing chamber, auxiliary means for supplying oxidant to said mixing chamber, means for varying the supply of the sample and oxidant mixture to the mixing chamber, and means for adjusting the flow of oxidant through said auxiliary supply means in response to a variation in the supply of oxidant supplied by said sample and oxidant supply means such that the total oxidant flow supplied to said burner remains substantially constant.
2. A gas flow control system for an atomic absorption spectrometer having a burner for burning a mixture of fuel, oxidant and a sample comprising:
means for supplying fuel to the burner, means for supplying sample to the burner including means for adjusting the supply of sample to optimize the measured signal of the spectrometer and first means for supplying oxidant to the burner, the supply of oxidant to the burner through said first means being adjustable in accordance with the adjustment to said sample adjustment means, second means for providing an adjustable supply of oxidant to the burner, the total supply of oxidant to the burner being equal to the sum of the oxidant supplied to the burner by said first and second oxidant supply means, and means for adjusting said second oxidant supply means in response to an adjustment of said sample flow means to maintain the total oxidant supplied to the burner substantially constant.
means for supplying fuel to the burner, means for supplying sample to the burner including means for adjusting the supply of sample to optimize the measured signal of the spectrometer and first means for supplying oxidant to the burner, the supply of oxidant to the burner through said first means being adjustable in accordance with the adjustment to said sample adjustment means, second means for providing an adjustable supply of oxidant to the burner, the total supply of oxidant to the burner being equal to the sum of the oxidant supplied to the burner by said first and second oxidant supply means, and means for adjusting said second oxidant supply means in response to an adjustment of said sample flow means to maintain the total oxidant supplied to the burner substantially constant.
3. The system according to claim 2 wherein said first and said second oxidant supply means include discrete first and second conduits respectively, said adjusting means for said second oxidant supply means including means for sensing the flow of oxidant through said first conduit and means responsive to said sensing means for adjusting the supply of oxidant through said second conduit to compensate for changes in the supply of oxidant through said first conduit whereby total oxidant flow to the burner remains substantially constant.
4. The system according to claim 3 wherein said sensing means includes a restriction in said first conduit for developing a pressure differential there-across proportional to the flow of oxidant therethrough, pressure monitoring means coupled to said sensing means on opposite sides of said restric-tion, and means responsive to the pressure monitored by said pressure monitoring means for adjusting the flow of oxidant through said second conduit.
5. The system according to claim 4 including means for providing a reference pressure signal, said adjusting means for said second conduit being responsive to said reference pres-sure signal and said pressure monitoring means to adjust the flow of oxidant through said second conduit to satisfy the equation P = A + B - C, where P is the pressure of the oxidant supplied by said second conduit to the burner, B is the reference signal pressure and A and C are the pressures on the respective opposite sides of the restriction.
6. An automatic gas flow control apparatus for an atomic absorption spectrometer instrument system including means for burning a mixture of fuel, oxidant and an unknown element-containing sample, which comprises:
means for supplying a predetermined flow of the fuel to the burner means;
means for introducing a variable flow of sample containing the unknown element to the burner including means adjustable to vary the sample flow so as to optimize the measured signal of said spectrometer, said sample adjusting means including means for supplying oxidant to said burner, the flow of the oxidant supplied to said burner being dependent upon the adjustment made for supplying sample;
means for supplying a variable flow of oxidant to the burner, the varying flow supplied being equal to the difference between a predetermined total flow of oxidant required for a prescribed sensitivity of the spectrometer and the varying amount supplied by said sample introducing means;
means for sensing the flow of oxidant supplied to the sample introducing means and to the burner by said variable oxidant supply means;
means for comparing the sensed flow of oxidant to the sample introducing means and to the burner by said variable oxidant supply means to the predeter-mined total flow of oxidant required for a pre-scribed sensitivity of the spectrometer; and means for adjusting the flow of oxidant to said burner by said variable oxidant supply means, in response to said comparing means, to compensate for said adjustment to said sample introducing means, whereby the predetermined total flow of oxidant to the burner is maintained substantially constant.
means for supplying a predetermined flow of the fuel to the burner means;
means for introducing a variable flow of sample containing the unknown element to the burner including means adjustable to vary the sample flow so as to optimize the measured signal of said spectrometer, said sample adjusting means including means for supplying oxidant to said burner, the flow of the oxidant supplied to said burner being dependent upon the adjustment made for supplying sample;
means for supplying a variable flow of oxidant to the burner, the varying flow supplied being equal to the difference between a predetermined total flow of oxidant required for a prescribed sensitivity of the spectrometer and the varying amount supplied by said sample introducing means;
means for sensing the flow of oxidant supplied to the sample introducing means and to the burner by said variable oxidant supply means;
means for comparing the sensed flow of oxidant to the sample introducing means and to the burner by said variable oxidant supply means to the predeter-mined total flow of oxidant required for a pre-scribed sensitivity of the spectrometer; and means for adjusting the flow of oxidant to said burner by said variable oxidant supply means, in response to said comparing means, to compensate for said adjustment to said sample introducing means, whereby the predetermined total flow of oxidant to the burner is maintained substantially constant.
7. The apparatus of claim 6 further comprising a pneumatic computing means including an oxidant inlet port, an oxidant outlet port, pressure command means and pressure moni-toring means, said pressure command means being responsive to a command pressure proportional to the predetermined total flow of oxidant desired to the burner, said pressure monitoring means being responsive to said flow sensing means, said com-puting means being operative in response to said pressure command means and said pressure monitoring means to adjust the flow of oxidant between said inlet port and said outlet port to compensate for variations in the flow of oxidant through said sample introducing means.
8. The apparatus of claim 7 wherein the means for sensing the flow of oxidant supplied to the sample introducing means includes means in line with the oxidant supply to said sample introducing means, said in-line means developing a pressure differential there-across proportional to the flow of oxidant therethrough, said pressure monitoring means including first and second ports connected to respective sides of said in-line means, whereby said computing means in response to said pressure command means and the pressure differential across said in-line means, adjusts the flow of oxidant between said inlet port and said outlet port to satisfy the equation, P=A+B-C, where P is the pressure at the oxidant outlet port, B
is the command pressure and A and C are the pressures on respec-tive sides of the in-line means.
is the command pressure and A and C are the pressures on respec-tive sides of the in-line means.
9. The apparatus of claim 8, wherein said computing means includes means for mechanically adjusting same, whereby the pressure at the oxidant outlet port can be adjusted to assure the lowest required flow rate of oxidant therethrough for the minimum command pressure.
10. The apparatus of claim 8 wherein said in-line means is a restrictor.
11. The apparatus of claim 7 further comprising means for converting an electrical signal symbolizing the predeter-mined total flow of oxidant required for a prescribed sensitivity of the spectrometer into said command pressure.
12. The apparatus of claim 11 further comprising means for converting an electrical signal symbolizing said predeter-mined flow of the fuel to said burner means into an equivalent pressure, said apparatus further including means pneumatically responsive to said equivalent pressure to thereby supply said predetermined flow of fuel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90744978A | 1978-05-22 | 1978-05-22 | |
| US907,449 | 1978-05-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108432A true CA1108432A (en) | 1981-09-08 |
Family
ID=25424110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA306,363A Expired CA1108432A (en) | 1978-05-22 | 1978-06-28 | Automatic gas flow control apparatus for an atomic absorption spectrometer burner |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS54161989A (en) |
| AU (1) | AU516406B2 (en) |
| CA (1) | CA1108432A (en) |
| DE (1) | DE2833553A1 (en) |
| GB (1) | GB1588478A (en) |
| IT (1) | IT1116208B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2113831B (en) * | 1982-01-19 | 1985-10-02 | Philips Electronic Associated | Method of analysis using atomic absorption spectrophotometry |
| DE3307409A1 (en) * | 1983-03-02 | 1984-09-06 | Kosizky, Wladimir, Dr., 8000 München | ATOMIC ABSORPTION SPECTROPHOTOMETER WITH FEEDBACK |
| DE3407552A1 (en) * | 1984-03-01 | 1985-09-05 | Bodenseewerk Perkin Elmer Co | GAS CONTROL DEVICE FOR CONTROLLING THE FUEL GAS AND OXIDE SUPPLY TO A BURNER IN AN ATOMIC ABSORPTION SPECTROMETER |
| US4617953A (en) * | 1984-11-13 | 1986-10-21 | Kendall Tobias Michael W | Fluid flow control system |
| US4568267A (en) * | 1984-11-13 | 1986-02-04 | The Perkin-Elmer Corporation | Safety apparatus for an atomic absorption spectrophotometer burner |
| DE3531276A1 (en) * | 1985-09-02 | 1987-03-05 | Bodenseewerk Perkin Elmer Co | METHOD AND DEVICE FOR DETERMINING THE ZERO LINE IN ATOMIC ABSORPTION SPECTROMETERS |
| DE3532537A1 (en) * | 1985-09-12 | 1987-03-19 | Bodenseewerk Perkin Elmer Co | DEVICE FOR ENDING A FLAME IN AN ATOMIC ABSORPTION SPECTROMETER |
| JP4779807B2 (en) * | 2006-05-29 | 2011-09-28 | 株式会社島津製作所 | ICP emission spectrometer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1420599A (en) * | 1972-02-02 | 1976-01-07 | Pye Ltd | Apparatus for chemical analysis including a burner |
-
1978
- 1978-05-30 GB GB24664/78A patent/GB1588478A/en not_active Expired
- 1978-06-28 CA CA306,363A patent/CA1108432A/en not_active Expired
- 1978-07-03 AU AU37714/78A patent/AU516406B2/en not_active Expired
- 1978-07-31 DE DE19782833553 patent/DE2833553A1/en active Granted
- 1978-10-19 JP JP12792078A patent/JPS54161989A/en active Granted
-
1979
- 1979-05-22 IT IT49134/79A patent/IT1116208B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| DE2833553A1 (en) | 1979-11-29 |
| GB1588478A (en) | 1981-04-23 |
| DE2833553C2 (en) | 1987-10-01 |
| AU3771478A (en) | 1980-01-10 |
| JPS6128293B2 (en) | 1986-06-30 |
| IT7949134A0 (en) | 1979-05-22 |
| JPS54161989A (en) | 1979-12-22 |
| AU516406B2 (en) | 1981-06-04 |
| IT1116208B (en) | 1986-02-10 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19980908 |